Highly scalable distributed database

https://cassandra.apache.org/

Header-only test framework for C++

https://github.com/catchorg/Catch2

MS Word/Excel converter to plain ASCII or TeX. TK viewer included

http://www.wagner.pp.ru/~vitus/software/catdoc/

Coin-or Branch and Cut: mixed integer programming solver

https://projects.coin-or.org/Cbc

Reference implementation of the C interface to the legacy Fortran BLAS

https://www.netlib.org/blas/blast-forum/

Tool to minimize the compile time of C/C++ programs

https://ccache.samba.org/

CDDB client bundle GNUstep

https://gsburn.sourceforge.net/

Compare directories and select files to copy

http://home.hccnet.nl/paul.schuurmans/linux/index.html#xdircmp

CDDA extraction tool (also known as ripper)

https://www.xiph.org/paranoia/

Record CD-R[W]s in disk-at-once mode

http://cdrdao.sourceforge.net/

Command-line CD/DVD writing suite

http://www.cdrkit.org/

Tool to lookup CD-ROM dictionaries

https://www.nerimadors.or.jp/~jiro/cdrom2/

CD/DVD/BluRay and ISO-9660 image creation and extraction tools

http://cdrtools.sourceforge.net/private/cdrecord.html

Cellular phone-number read/write tool (in Japan only)

http://www.nurs.or.jp/~kurati/celrw/

Vector graphics tool for GNUstep

http://www.cenon.info/dLinux_gb.html

C++11 library for serialization

https://github.com/USCiLab/cereal

Library for reading and writing files in FITS data format

https://heasarc.gsfc.nasa.gov/fitsio/ https://github.com/HEASARC/cfitsio

Cryptographic file system implemented as a user-space NFS server

https://www.bayofrum.net/cgi-bin/fossil/cfs/

Computational geometry library

https://www.cgal.org/

GIF encoder written in C

https://github.com/dloebl/cgif

Fast, lightweight web frontend for Git repositories

https://git.zx2c4.com/cgit/about/

Collection of cut generators for COIN-OR packages that use cuts

https://github.com/coin-or/Cgl

Character art facsimile generator

https://hpjansson.org/chafa/

Embedded scripting language designed for C++

https://chaiscript.com/

Tiling X11 window manager and Vulkan compositor

https://jaelpark.github.io/chamferwm-docs/

Charis SIL TrueType font collection

https://software.sil.org/charis/

Charis SIL TrueType font collection, compact variant

http://scripts.sil.org/cms/scripts/page.php?item_id=CharisSILfont

Japanese Morphological Analysis System

Unit test framework for C

https://libcheck.github.io/check/

Find processes that need restarting after an upgrade

https://github.com/Freaky/checkrestart

Photobooth-inspired app for taking pictures and videos from webcam

https://www.gnome.org/projects/cheese/

Feelter thet cunferts Ingleesh text tu Muck Cheenese-a

http://mysite.verizon.net/ebrowne72/chef/index.html

Chinese traditional calendar

https://github.com/WhiredPlanck/chinese-calendar

FUSE based filesystem with replication at the filesystem level

https://BSDforge.com/projects/sysutils/fusefs-chironfs/

Utility to quickly check multiple folders for new email

Tool to locally check for signs of a rootkit

http://www.chkrootkit.org/

Library for dealing with Microsoft ITSS/CHM format files

http://www.jedrea.com/chmlib/

AcoustID audio fingerprinting library

https://acoustid.org/chromaprint

Tool to chroot softwares easily

https://sourceforge.net/projects/chrootsafe/

Tool to modify DT_RPATH in existing ELF binaries

Synchronise computer clock to CHU radio station

https://www.rossi.com/chu/

Control center for Cinnamon

https://github.com/linuxmint/cinnamon

Additional UI API for cinnamon

https://github.com/linuxmint/cinnamon

Additional UI API for cinnamon

https://github.com/linuxmint/cinnamon-menus

Cinnamon screen saver and locker

https://github.com/linuxmint/cinnamon-screensaver/

Session component for the cinnamon desktop

https://github.com/linuxmint/cinnamon

Cinnamon desktop settings daemon

https://github.com/linuxmint/cinnamon

Translations for the cinnamon desktop

https://github.com/linuxmint/cinnamon-translations/

Tool to compress ISO images to CSO format

https://github.com/laffer1/ciso-maker

Open-source (GPL) anti-virus engine (Regular Feature Release)

https://www.clamav.net/